Field of the Invention
The present invention relates to a dual clutch, in particular a multi-plate dual clutch for coupling a drive shaft of a motor vehicle engine to a transmission shaft of a motor vehicle transmission and/or an auxiliary output shaft of an auxiliary power take-off of the motor vehicle, in particular a power take-off shaft. The dual clutch includes a drive clutch for coupling the motor vehicle engine with the transmission shaft and an auxiliary power take-off clutch for coupling the motor vehicle engine with the auxiliary output shaft. The drive clutch and the auxiliary power take-off clutch are each to be actuated independently of one another by means of a separate lever mechanism.
Description of the Related Art
Dry dual clutches that are installed outside of the transmission on the vehicle and are actuated mechanically are known from the prior art. Such conventional dual clutches have a first clutch for driving operation, the so-called drive clutch or drive shaft clutch, and a second clutch for an auxiliary drive, for example a power take-off drive, the so-called auxiliary drive clutch or power take-off drive clutch. A distinction is made between conventional dual clutches, in which the drive shaft clutch and the power take-off shaft clutch are engaged in the deactivated state, and safety clutches (so-called safety PTO dual clutches), in which the drive shaft clutch is engaged in the deactivated state and the power take-off shaft clutch is disengaged in the deactivated state.
It is disadvantageous that in such known dry dual clutches the maximum thermal absorptive capacity of the clutches and the maximum thermal capacity of the clutch linings as a rule is quickly reachable, in particular when transmitting high torques. Increasing the transmissible torque while keeping the construction size the same is therefore limited. In the critical load range, high wear of the friction linings and a resulting change of the operating points and clamping forces is therefore the negative consequence.
Added to the problem situation described above is the fact that the average power of motor vehicles using dual clutches, for example tractors, and thus the demands on the clutches, are constantly growing. Present-day tractor dual clutches have reached their performance limits in some cases, especially with regard to thermal demands.
In WO 2006/084435 A1 a clutch unit is disclosed having a housing that is attachable to a flywheel. To make a first and a second clutch in that clutch unit two contact plates are contained which are non-rotating relative to the housing but are axially movable, and to each of which a clutch disk is assigned. The clutches are actuatable independently of one another by means of lever arrangements that are swivel-mounted on the housing, wherein one lever arrangement is coupled with each contact plate to disengage and engage the corresponding clutch The first clutch facing the flywheel is engaged in the non-actuated state by means of a diaphragm spring clamped between its contact plate and the housing, the diaphragm spring being positioned axially between the adjacent contact plates. The second clutch, provided on the side of the first clutch facing away from the flywheel, is disengaged in the non-actuated stage and is forced closed by a force exerted on its lever arrangement, the lever arrangement of the second clutch being coupled with the assigned contact plate by means of axially operative tensile elements. There is at least one spring element clamped between the tensile elements and the contact plate, which has a predetermined pre-tensioning when the second friction clutch is disengaged and undergoes an additional elastic deformation as the second clutch is engaged.
In DE 10 2012 207 244 A1 a clutch arrangement is disclosed for use in the drive train of a tractor, including a drive clutch and an auxiliary drive clutch, wherein the drive clutch is positioned between an internal combustion engine and a transmission input shaft, and the auxiliary drive clutch is positioned between the internal combustion engine and an auxiliary drive, wherein the clutch arrangement includes a clutch housing having a formed sheet metal part.
In DE 10 2013 214 966 A1 a dual clutch is disclosed for coupling a drive shaft of a motor vehicle engine with a transmission shaft of a motor vehicle transmission, and/or an auxiliary power take-off of the motor vehicle, in particular a power take-off shaft. The dual clutch includes a first friction clutch for frictionally pressing a first clutch disk that is couplable with the transmission shaft between a first contact plate and a first counter plate, wherein the first contact plate is movable in an axial direction to engage the first friction clutch. A second friction clutch is included for frictionally pressing a second clutch disk that is couplable with the auxiliary power take-off between a second contact plate and a second counter plate, wherein the second contact plate is movable in the axial direction to engage the second friction clutch. A first actuating element is provided to move the first contact plate and a second actuating element is provided to move the second contact plate, wherein the second contact plate is connected to a thrust ring that is operationally connected to the second actuating element to transmit the displacing movement. A pre-stressed pressure storage element is positioned between the second actuating element and the thrust ring.
In DE 10 2013 215 079 A1 a dual clutch is disclosed for coupling a drive shaft of a motor vehicle engine with a transmission shaft of a motor vehicle transmission and/or to an auxiliary power take-off of the motor vehicle, in particular a power take-off shaft. The dual clutch includes a first friction clutch for frictionally pressing a first clutch disk that is couplable with the transmission shaft between a first contact plate and a first counter plate, wherein the first contact plate is movable in an axial direction to engage the first friction clutch. A second friction clutch is provided for frictionally pressing a second clutch disk that is couplable with the auxiliary power take-off between a second contact plate and a second counter plate, wherein the second contact plate is movable in the axial direction to engage the second friction clutch. The dual clutch includes a first actuating element to move the first contact plate and a second actuating element to move the second contact plate. The second contact plate is connected to a thrust ring that is operationally connected to the second actuating element to transmit the displacing movement. The second actuating element has at least one spring element for pre-biasing, wherein the at least one spring element is positioned between the second actuating element and the thrust ring.
Starting from the above-identified prior art, an object of the present invention is to develop a dual clutch that can absorb and remove more frictional heat with the same or only slightly greater construction space, and, in addition, offers easy increase of the maximum torque. The dual clutch in accordance with the present invention should be capable of replacing known dual clutches with minimal modification effort and expense for the customer (a plug-in solution).